Rigid Metal Conduit Support

[brother]

I always thought you could (and have seen it in grocerty stores) support rigid (rmc) every 20ft in a vertical riser when it was not practical to support it within the 3 ft of boxes etc, 10ft thereafter. I read the NEC 2005 CODE and it says for industrial machinery or 'fixed equipment'. So i assume that these store racks are 'fixed' equipment when they have a j box on top, or was this a change over the years??

 

[Lcdrwalker]

It's only been in the last ten or twelve years that I have attached conduit to shelving in this manner. The reason is that now these big box stores anchor the shelving to the floor, hence 'fixed'. The old method was to run RMC from floor to ceiling with a 'T' fitting in the run. We would then use LT or FMC ot feed the loads on the shelves.

 

[iwire]

As a side note the roof deflection caused by snow loads can make those vertical risers get 'S' shaped.

A steel truss roof settles a lot under snow loads, if you in the middle of the span make sure the pipe is not connected firmly to the truss, make it so it can slid. (Leave the minni, strut clip loose.

 

[mivey]

As a side note the roof deflection caused by snow loads can make those vertical risers get 'S' shaped.

A steel truss roof settles a lot under snow loads, if you in the middle of the span make sure the pipe is not connected firmly to the truss, make it so it can slid. (Leave the minni, strut clip loose.

Now there's something I would not have thought about. We don't have much of a snow problem.

 

[iwire]

Now there's something I would not have thought about.

You don't think of it until you walk into the job the morning after a heavy snow and see what was nice looking work now looking bad. :grin:

 

[brother]

As a side note the roof deflection caused by snow loads can make those vertical risers get 'S' shaped.

A steel truss roof settles a lot under snow loads, if you in the middle of the span make sure the pipe is not connected firmly to the truss, make it so it can slid. (Leave the minni, strut clip loose.

You mean to tell me that that much (snow) wait is on those roofs that can make rigid METAL conduit bend like that?? Im thinking that rigid METAL would be the tuffest in town, the roof may sag, the wind my blow, but the rmc will stand.

 

[iwire]

You mean to tell me that that much (snow) wait is on those roofs that can make rigid METAL conduit bend like that?? Im thinking that rigid METAL would be the tuffest in town, the roof may sag, the wind my blow, but the rmc will stand.

A few sticks of 1/2 rigid is not going to stop a few tons of snow from sagging the trusses.

 

[quogueelectric]

I have wired many machines just this way with a floor flange and a t condulet. We dont use many trusses around here though.